Process of making tracings



INVENTORS. y L. Ja/men a g ATTORNEY 2 Sheets-Sheet 1 Filed 001.. 20, 1927 R. L. JANNENGA ET AL PROCESS OF MAKING TRACINGS I I I l l I I I l i I I Nov. 19, 1929.

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R. L. JANNENGA ET AL PROCESS OF MAKING TRACINGS Filed Oct. 20. 1927 ZSheetS-Sheet 2 A 4 VZ/i Xli A I 'ATTORNEY Patented Nov. 19, 1929 UNITED STATES PATENT orrlcr.

BOY L. J'ANNENGA AND ROBERT C. LEMMERHART, OF EAST PITTSBURGH, PENNSYL- VANIA, ASSIGNOBS TO .WESTINGHO'USE ELECTRIC AND KAN UFACTURIN G COIPANY,

A CORPORATION OF PENNSYLVANIA PROCESS OF MAKING TBACINGS Application fled mm 20, 1927. Serial 1n.- aa'iaso.

Our invention relates to processes of making tracings from which multiple coples may be made and it has specific relation to a simplified process for making tracings 1n WhlCh a number of standard symbols are used.

' An Object of our invention is to simplify and shorten the process of preparlng traelngs.

Another object of our invention is to shorten the time consumed in making tracings in which a plurality of standard symbols appear.

The process of making blue-prints consists, essentially, in drawing the des red figures on a sheet of transparent'materlal, such as a specially prepared linen or a transparent pa er, placing the tracing so formed against a s act of glass and placing a sheet of sensitized paper against the tracing. The tracin and sensitized paper are then exposed to lig t and, when the paper is developed, the lines of the tracing appear as whlte llnes against a blue back-ground. The blue print is, in fact, a ne ative of the traclug, since the black lines o the tracing form the whlte areas of the blue print.

In c rtain types of work, a number of s ,mbo 1c representations are used, and the rawing of these symbolic representations consumes a great portion of the time required in making the drawing on the tracing cloth. Our invention simplifies this rocess and materially reduces the time use inmaking the tracing.

Our invention may be better understood by reference to the accompanying drawings, in which like figures indicate like parts.

Figure 1 is a face view of a sectionallzed sheet of symbolic representations of electric machinery, such as switches and controllers;

40 Fig. 2 is a sectional view showing various symbolic representations or symbol stickers 7 applied to the underside of a sheet of tracing paper; and

Fi 3 is a face view of the symbol stickers applied to the undersideof the tracing paper, connections having been drawn between points of the symbols to indicate the complete electrical circuit.

In practicing our invention, the first step is to make up a number of symbol stickers 1, 2 and 3 such as are shown in Fig. 1. This is done by drawing the symbols, such as the switch connections shown in Fig. 1, on a transparent material, such as aper or linen. From the sheet so prepare a negative is made according to the well known photoengraving or photo-lithographic process. In the photo-lithographic process, the usual zinc etching is prepared and is used to print a numberof sheets of symbol stickers, such as shown in Fig. 1. The printed lines 4.- thus constitute opaque bodies on the transparent sheet of paper 5 (Fig. 2) A coating of glue or other adhesive material 6 is applied to the face of the sheet which is preferably perforated between the symbols, as indicated b dotted lines, so that each symbol'may be rea ily disengaged. The sheets may be provided with two small holes 7 at the left side, so that they ma be bound into books convenient for the dra tmens use.

If, for instance, a draftsman wishes to make a tracing of a certain wiring diagram, such as the one shown in Fig. 3, he selects the proper symbol stickers from a sheet, such as shown in Fig. 1, and permanently applies them' to the underside of the usual tracing sheet 8. The draftsma-n then sup lies the lines 9 connecting the various sym ols and supplies any figures or wording which may be necessary.

Referrin to Fig. 3, for instance, it will be seen that t e Figures 1, 2 and 3 which are supplied by the symbol stickers, represent the greater part of the drawing and that only a small part of the draftsmans time is consumed in connecting up the various points on the drawings.

From thetracing so produced, a brown negative print or a brownie is prepared. Since the symbol stickers constitute a second layer beneath the layer upon which the lines are drawn, the area covered by the symbol sticker appears on the brownie as a light grayish area. A master tracing is then printed from the brownie. The grayish area on. the brownie appears on the print but is removed during the developing process.

From the master tracing, any number of blue prints may be made according to the a well known blue-printing" process hereinbefore described. Any minor additions or chan es may be made on the master tracing.

It is obvious that some of the steps herein described may be eliminated or the process ma be altered, for instance, the symbol stic er may be applied to the upper side of the tracing sheet and the connecting lines made accordingly. Such modifications may be made without departing from the spirit and scope of our invention, as defined in the appended claims.

We claim as our invention:

1. A tracing comprising a sheet of material havin fi res thereon and applicable members aving symbolic figures thereon attached to a face 'of said sheet, the figures on the sheet bein drawn-so that they will connect the symbo '0 members.

2. A tracing comprising a trans arent sheet of material having opa ue gures thereon and transparent a plicab e members having opaque symbolic gures thereon attached to a face of said sheet, the figures on the sheet being drawn so that they will connect the symbolic members.

3. The process of making prints comprising superimposing a semi-transparent member upon another to provide a semi-transparent composite member, placing a sensitized sheet on the composite member, and making a print from said compdsite member by exposing the sensitized sheet to the light rays which have passed through said semitransparent composite member.

4. A process of making blue prints comprising providing transparent stickers hav ing conventionalsymbols printed thereon, at taching them by gluing to the reverse side of a transparent sheet of drawing paper, drawing various figures on the obverse side of said transparent sheet, printing a negative print from the drawing so secured, making a master tracing therefrom and making blue prints from said master tracing.

5. A tracing comprising a transparent sheet of paper, applicable members, having symbols thereon, attached to said paper and manually drawn lines connecting a plurality of said symbols.

6. A tracing comprising a transparent sheet of paper, applicable members, having symbols printed thereon, attached to one side of said sheet, said symbols appearing on the obverse side of said sheet as parts of a drawing, and manually drawn lines connecting a plurality of said symbols to form the complete drawing.

7. A tracing comprising a transparent sheet of paper, a plurality of applicable members attached to one side of said sheet and having symbols printed thereon which represent conventional parts of a wiring diagram, said symbols appearing on the obverse side of the sheet as parts of a drawing, and manually drawn lines connecting the symbols to form a complete drawing.

8. The process of making a tracing which comprises attaching transparent stickers, having symbolic figures t ereon forming parts of a drawing, to a trans arent sheet and connecting a plurality of sai symbols .by

'means of manually drawn lines.

9. The process of making a tracing which comprises. attachin transparent stickers, having printed sym olic figures thereon, to the reverse side of a transparent sheet of paper so that the symbols will appear on the obverse side as portions of a drawing and connecting a plurality'of said symbols together by means of lines manually drawn on the o v 

